1. Field of the Invention
The present invention relates to a modular system with a mounting apparatus for the mounting of shaft prostheses.
2. Description of the Prior Art
FR-A-2 727 857 shows a shaft prosthesis for a shoulder joint which consists of a stem and a prosthesis head which are connected to one another via a fixable ball joint. The prosthesis head consists of a shallow spherical section, the underside of which is to lie on a planar resection surface of a humerus in order to completely cover off the resection surface. A spherical body which stands off from the stem in an inclined direction to the stem axis is divided up by slits into lobes which can be spread apart by a thorn which is driven into the spherical body through the stem in the inclined direction. In the prosthesis head a spherical bearing shell is worked in from the lower side which encloses the spherical body during the spreading apart and blocks it at a selectable angle to the stem axis. A disadvantage of this arrangement is that this setting of the inclination must be done in advance and that a considerable spatial imagination is required of the surgeon. Since the dimensions of the fixable ball joint must be kept small for reasons of space, a plastic deformation at the feet of the lobes is compulsory during their fixing and self inhibition is necessary in a spreading thorn for safety. This means that, with all the other advantages of this construction, the surgeon actually has only one chance in order to definitively fix the coupling.